JP7484007B2 - How to build a building - Google Patents

Description

This disclosure relates to a pile foundation, more specifically, a pile foundation having a footing that joins a column to a pile and a foundation beam that connects adjacent footings, a building having this pile foundation, a method for constructing this building, a method for using this building, and a method for renovating this building.

A known footing structure foundation is one in which a column is supported by a pile using a footing member made of precast concrete (see Patent Document 1). In this footing structure pile foundation, a female thread member for connection that does not protrude from the top surface is formed on the top surface of the footing member, and a foundation beam constructed in contact with the top surface of the footing member is connected to the female thread member, making it easy to construct the foundation beam. Specifically, the foundation beam is constructed from cast-in-place concrete that is connected to the footing member via a male thread member screwed into the female thread member of the sleeve.

JP 2017-057642 A

However, the footing structure pile foundation described in Patent Document 1 takes a long time to construct because the foundation beams are constructed from cast-in-place concrete.

In light of this background, the objective of the present invention is to enable rapid construction of pile foundations.

In order to solve such problems, one embodiment of the present invention is a pile foundation (2) comprising a plurality of piles (3) arranged in positions aligned with columns (11), a plurality of footings (4) integrally provided on the heads of the plurality of piles and supporting the corresponding columns, and a foundation beam (5) connecting a pair of adjacent footings, the foundation beam being made of precast concrete having a first cross-sectional enlarged portion (21) with a first sheath (22) extending in the material axis direction formed at both ends, and the both ends (21) of the foundation beam being pressed against the corresponding footing by a first tension member (24) inserted into the first sheath. Here, a footing is a structure that connects a column to a pile, and is not required to be buried in the ground or supported by the ground. A foundation beam is a beam that connects a pair of footings, and is not required to be buried in the ground or supported by the ground.

With this configuration, the foundation beam is made of precast concrete and is connected to the footing by the first tendon, which shortens the time required to construct the pile foundation.

Preferably, the first tendon is an unbonded tendon that is not attached to the footing or the foundation beam.

With this configuration, the foundation beam is attached to a pair of footings by the first tendon, which is an unbonded tendon that is not attached to the footings or the foundation beam. Therefore, when the building is demolished, the foundation beam can be reused by releasing the connection by the first tendon.

Preferably, the footing (4) and the foundation beam (5) are provided at a position above the ground surface (GL). Here, the ground surface means the surface of the ground before the pile foundation is constructed, and does not include the surface of the ground excavated for the construction of the pile foundation.

With this configuration, there is no need to excavate the ground when constructing the footing and foundation beams. Therefore, the time required to construct the pile foundation can be reduced compared to constructing the footing and foundation beams after excavating the ground.

Preferably, the footing (4) and the foundation beam (5) are positioned higher than the ground surface (GL), the upper part of the pile (3) protruding upward from the ground surface is exposed below the footing, and a space (S) on the lowest floor in which equipment machinery (41) can be installed is formed between the ground surface and the underside of the foundation beam.

With this configuration, the foundation beams can function as beams to support the slab of the second floor from the bottom. In other words, the upper part of the pile foundation can function as the lowest floor structure of a normal superstructure. Therefore, the time required to construct the superstructure can be reduced by one floor.

Preferably, the footing (4) is made of precast concrete having a lower surface on which a first recess (51) that is open downward and has a cross section larger than that of the pile (3) is formed, and a second sheath (23) that extends in the material axis direction of the foundation beam (5), and the head of the pile is received in the first recess and the first recess is filled with a filler material (55).

According to this configuration, a first recess larger than the cross section of the pile is formed on the underside of the PCa member that forms the footing, so even if the planar position of the pile head deviates from the planned position of the column, the PCa member that forms the footing can be positioned to match the planned position of the column and joined to the pile via filler. In addition, because the footing is made of precast concrete, the time required to construct the pile foundation can be reduced compared to constructing a footing with cast-in-place concrete.

Preferably, the footing (4) is made of cast-in-place concrete, and a second sheath (23) is embedded inside the footing so as to be continuous with the first sheath (22) of the first cross-sectional enlargement portion (21).

With this configuration, even if the planar position of the pile head deviates from the planned position of the column, the footing can be easily constructed at a position that matches the planned position of the column. In addition, since the second sheath is embedded inside the footing, the first tendon can be positioned to penetrate the footing, and the foundation beam can be pressed against the footing by the first tendon.

In order to solve the above problem, one embodiment of the present invention is a building (1) comprising a pile foundation (2) of the above configuration and a superstructure (10) supported by the pile foundation, the superstructure comprising a plurality of PCa columns (13, 14) made of precast concrete supported by a plurality of footings (4) and a PCa beam (15) made of precast concrete connecting a pair of adjacent PCa columns, the PCa beam having a second cross-sectional enlargement portion (26) with a third sheath (27) extending in the member axial direction at both ends, the PCa column having a fourth sheath (28) continuous with the third sheath, and the both ends (26) of the PCa beam are pressure-bonded to the corresponding PCa column by a second tension member (29) inserted through the third sheath and the fourth sheath.

With this configuration, the superstructure can be constructed using PCa columns and PCa beams, which reduces the time required to construct not only the pile foundation but also the superstructure. In addition, since the PCa beam is crimped to a pair of PCa columns by the second tendon, the second tendon is an unbonded tendon that is not attached to the PCa column and PCa beam. When the building is demolished, the connection by the second tendon can be released and the PCa beam can be reused.

In a configuration in which the footing (4) is made of precast concrete with the first recess (51) on its underside, preferably, an anchor (56) is embedded in the footing so as to protrude upward from its upper surface, and the PCa column (13) has a fifth sheath (33) extending vertically, and is pressed against the footing by a third tendon (32) connected to the anchor of the footing and inserted through the fifth sheath.

With this configuration, the PCa column can be easily joined to the footing made of precast concrete using the third tendon. In addition, since the PCa column is pressure-bonded to the footing by the third tendon, the third tendon is an unbonded tendon that is not attached to the PCa column. When the building is demolished, the connection by the third tendon can be released, allowing the PCa column to be reused.

In a configuration in which the footing (4) is made of the cast-in-place concrete, preferably, a second recess (61) that opens upward is formed on the upper surface of the pile (3), an anchor (56) is embedded in the footing, the lower end of which is received in the second recess and arranged to protrude upward from the upper surface of the footing, and the PCa column (13, 14) has a fifth sheath (33) that extends vertically and is pressed against the footing by a third tendon (32) that is connected to the anchor of the footing and inserted into the fifth sheath.

With this configuration, the PCa column can be easily joined to the footing made of cast-in-place concrete by the third tendon. Furthermore, even if the planar position of the pile head deviates from the planned position of the column, an anchor of a length that allows its lower end to be received in the second recess can be provided in a position that matches the planned position of the column. Furthermore, since the PCa column is pressed to the footing by the third tendon, by making the third tendon an unbonded tendon that is not attached to the PCa column, when the building is removed, the connection by the third tendon can be released and the PCa column can be reused.

In order to solve the above problem, one embodiment of the present invention is a method for constructing a building (1) having the above configuration, comprising the steps of: arranging three or more of the footings (4) or the PCa columns (13) in a row (FIG. 16); arranging two or more of the foundation beams (5) or the PCa beams (15) in a straight line between a corresponding pair of the footings or a corresponding pair of the PCa columns (FIG. 16); and inserting a plurality of the footings or the PCa columns into the first cross-sectional enlarged portion of the foundation beam to be joined thereto or the second cross-sectional enlarged portion of the PCa beam so as to penetrate the footings or the PCa columns and the first cross-sectional enlarged portion of the foundation beam to be joined thereto or the second cross-sectional enlarged portion of the PCa beam. The method includes the steps of arranging the first tendon (24) or the plurality of second tendons (29) on the same straight line (FIG. 16), connecting the two or more first tendons or the second tendons arranged on the same straight line with a connecting tendon (71) to form a single long continuous tendon (72) (FIG. 16), and applying tension to the continuous tendon to fix both ends of the plurality of first tendons to the corresponding first cross-sectional enlargement portion or the footing, or fix both ends of the plurality of second tendons to the corresponding second cross-sectional enlargement portion or the column (FIG. 16).

According to this configuration, in order to press the adjacent ends of a pair of foundation beams or a pair of PCa beams arranged in a straight line on both sides of a footing or PCa column to the footing or PCa column, it is not necessary to apply tension to the first tendon or the second tendon for each footing or PCa column. Therefore, the time required for the pressing work between the footing and the foundation beam or the pressing work between the PCa column and the PCa beam can be shortened.

In order to solve the above problem, one embodiment of the present invention is a method of using the building (1) in which a first method of using the superstructure (10) as a parking lot (81) is selected without installing an interior unit (42) that can be used as a hospital room, and a second method of using the superstructure as a hospital ward (82) is selected by installing the interior unit inside the superstructure.

With this configuration, the parking lot can be changed to a hospital ward by installing the interior unit inside the superstructure, and the hospital ward can be changed to a parking lot by removing the interior unit from inside the superstructure, making it easy to change the use of the superstructure. Also, since the superstructure can be used as a parking lot or a hospital ward as needed, land and construction costs can be reduced compared to building both. Furthermore, since the superstructure can be used as a hospital ward by changing the use, the ward can be used in a shorter time than if a new ward was built when needed.

In order to solve the above problem, one embodiment of the present invention is a method for renovating the building (1) described above, which includes the steps of inserting an interior unit (42) that can be used as a hospital room into the superstructure (10) that was used as a parking lot (81) horizontally from the outside of the superstructure and fixing it to the inside of the superstructure, thereby renovating the superstructure into a hospital ward (82), or releasing the fixation of the interior unit in the superstructure that was used as the hospital ward and extracting the interior unit horizontally outward from the superstructure, thereby renovating the superstructure into the parking lot.

With this configuration, the superstructure can be used as a parking lot before the interior unit is installed inside the superstructure. When it is being used as a parking lot, the superstructure can be used as a hospital ward by installing the interior unit inside the superstructure when necessary. Also, by installing the interior unit inside the superstructure, the parking lot can be converted into a hospital ward, so the ward can be used in a shorter time than if a new ward were to be built. When the building is being used as a hospital ward, the superstructure can be used again as a parking lot by removing the interior unit from inside the superstructure.

In this way, the present invention makes it possible to rapidly construct pile foundations.

FIG. 1 is a perspective view showing a main part of a building according to the present invention. A plan view of the pile foundation shown diagrammatically along the line II-II in FIG. An enlarged view of part III in FIG. FIG. 4 is a plan view of the upper structure shown diagrammatically along line IV-IV in FIG. FIG. 3 is a plan view of a pile foundation corresponding to FIG. 2 of a building according to a first modified example. A schematic elevation of a building as seen from the direction of the arrow VI in FIG. An explanatory diagram of the construction procedure of the building shown in FIG. An explanatory diagram of the construction procedure of the building shown in Figure 1. An explanatory diagram of the construction procedure of the building shown in Figure 1. An explanatory diagram of the construction procedure of the building shown in Figure 1. FIG. 7 is an elevation view of a building according to a second modified example, corresponding to FIG. 4 corresponding to a plan view of a building according to a third modified example. FIG. 7 is an elevation view of a building according to a third modified example, corresponding to FIG. FIG. 4 is a schematic vertical cross-sectional view of the main part of the building shown in FIG. 3 with a part cut away. FIG. 15 is a longitudinal sectional view of a main part of a building according to a fourth modified example, the view corresponding to FIG. Building plan to illustrate tensioning procedure for tendons An explanatory diagram of the change of building use, showing (A) the parking lot, (B) the change procedure, and (C) the hospital wing. Floor plan of the building showing the first example of use of the hospital ward Floor plan of the building showing the second use of the hospital ward Elevation of the building showing the third use of the ward (A) is a perspective view showing an example of how piles are used, and (B) is a vertical cross-sectional view.

The following describes in detail an embodiment of the present invention with reference to the drawings.

As shown in FIG. 1, the building 1 is provided with a pile foundation 2. The pile foundation 2 is provided with a plurality of piles 3 arranged in the X direction (row direction) and the Y direction (beam direction) that are perpendicular to each other on a horizontal plane. The X direction and the Y direction are perpendicular to each other. A footing 4 made of reinforced concrete is integrally provided on the head of each pile 3. A pair of footings 4 adjacent to each other in the X direction or the Y direction are connected by a foundation beam 5 (5X, 5Y) made of reinforced concrete. The building 1 is also provided with a superstructure 10 built on the pile foundation 2 and supported by the pile foundation 2. The superstructure 10 is a rigid frame structure made of reinforced concrete, and is provided with a plurality of columns 11 provided at positions corresponding to the piles 3, and a plurality of beams 12 (12X, 12Y) that connect a pair of columns 11 adjacent to each other in the X direction or the Y direction.

The pile 3 may be a precast pile or a cast-in-place pile, and has a circular cross section with a diameter larger than the maximum cross-sectional dimension of the column base. The pile 3 is constructed with a construction error equal to or smaller than a predetermined tolerance with respect to the planned position that matches the planned position of the column 11. The footing 4 is rectangular and has two sides on a horizontal plane that are larger than the diameter of the pile 3. The footing 4 is constructed at a planned position that matches the planned position of the column 11. In this embodiment, the footing 4 is made of precast concrete and is joined to the head of the pile 3. The foundation beam 5 includes an X-direction foundation beam 5X extending in the X direction and a Y-direction foundation beam 5Y extending in the Y direction. The X-direction foundation beam 5X and the Y-direction foundation beam 5Y are each made of precast concrete, and both ends of the foundation beams 5 are joined to the corresponding footing 4 by a first tendon 24 (FIG. 3) described later. In this embodiment, the X-direction foundation beams 5X and the Y-direction foundation beams 5Y are precast prestressed concrete (hereinafter referred to as PCaPC) members to which prestress has been introduced.

The column 11 includes a PCa column 13 made of precast concrete that is constructed on the footing 4 and forms the main part of the column 11, and a PCa joint member 14 made of precast concrete that is constructed on the PCa column 13 and forms the joint part 11a of the column 11. A pair of PCa columns 13 and PCa joint members 14 form the column 11 of the first floor. The beam 12 includes an X-direction beam 12X extending in the X direction and a Y-direction beam 12Y extending in the Y direction. The X-direction beam 12X is composed of a PCa beam 15 made of precast concrete. The PCa joint member 14 is composed of a PCa column-beam member that is integrally formed with the joint part 11a of the column 11 and a part of the Y-direction beam 12Y extending from the joint part 11a in the Y direction. The Y-direction beam 12Y is composed of the beam parts of two PCa joint members 14 that are joined to each other. In this embodiment, the X-direction beam 12X and the Y-direction beam 12Y are PCaPC members.

The pile foundation 2 thus comprises a plurality of piles 3 arranged in positions aligned with the columns 11, a plurality of footings 4 integrally formed on the heads of the respective piles 3 and supporting the corresponding columns 11, and a foundation beam 5 connecting a pair of adjacent footings 4. The superstructure 10 comprises a plurality of PCa columns 13 supported by the plurality of footings 4, and a PCa beam 15 connecting a pair of adjacent PCa columns 13 in the X direction. In this embodiment, the PCa beam 15 connects the pair of PCa columns 13 via a PCa joint member 14.

The foundation beam 5, the column 11, and the beam 12 all have a substantially rectangular cross-sectional shape. Slabs (not shown) are constructed on the top of the foundation beam 5 and the top of the beam 12. The column 11 is constructed to the length of several stories, and the superstructure 10 is made into a multi-layer structure by constructing the X-direction beam 12X, the Y-direction beam 12Y, and the slab on each story. Note that FIG. 1 shows the state in which only one story of the superstructure 10 is constructed. Such a multi-layer rigid frame superstructure 10 can be used as a parking lot 81 (FIG. 17(A)), a logistics warehouse, an office building, an apartment building, a commercial facility, a medical facility (hospital ward 82 (FIG. 17(C))), a disaster evacuation shelter, etc. The building 1 of this embodiment is constructed for the purpose of using the superstructure 10 as a multi-layered multi-storey parking lot.

Figure 2 is a plan view of the pile foundation 2 shown typically along line II-II in Figure 1, and Figure 3 is an enlarged view of part III in Figure 2. As shown in Figures 1 to 3, the foundation beams 5 (5X, 5Y) have first cross-sectional enlarged parts 21 at both ends, the cross-sectional area of which is enlarged compared to the middle part in the material axis direction. The X-direction foundation beam 5X has a vertically long rectangular cross-sectional shape at the middle part in the material axis direction, and the first cross-sectional enlarged part 21 is enlarged over the entire beam structure compared to the middle part. On the other hand, the Y-direction foundation beam 5Y has an I-shaped cross-sectional shape at the middle part in the material axis direction, and the first cross-sectional enlarged part 21 is enlarged at the middle part of the beam structure compared to the middle part. A plurality of first sheaths 22 (Figure 3) extending in the material axis direction are embedded in the first cross-sectional enlarged part 21 of each of the X-direction foundation beams 5X and the Y-direction foundation beams 5Y so as to open into the enlarged part.

In the footing 4, a plurality of second sheaths 23 extending in the X-direction and Y-direction, which are the material axis directions of the foundation beam 5 (5X, 5Y), are embedded. The second sheaths 23 are disposed in a position continuous with the first sheaths 22. The first cross-sectional enlarged portions 21 of the foundation beam 5 at both ends are crimped to the corresponding footing 4 by the first tendons 24 inserted through the first sheaths 22 and second sheaths 23. The first tendons 24 are unbonded tendons. Here, the unbonded tendons refer to tendons using an unbonding method in which the tendons are not attached to the PCa concrete members such as the foundation beam 5 and the footing 4 by not filling the sheaths with grout. The unbonded tendons may be, for example, PC steel wires, PC steel strands, carbon fiber cables, aramid fiber cables, and fiber bars (fiber cables hardened and integrated with resins, etc.). In this embodiment, PC steel wires are used as unbonded tendons.

Specifically, fixing devices 25 are provided on both ends of the first tension member 24. The fixing devices 25 include a support plate, an anchor head supported by the support plate, and a wedge that fixes the first tension member 24 to the anchor head. When the fixing devices 25 are attached to the ends of the first tension member 24 while tension is being applied to the first tension member 24, the tension of the first tension member 24 is maintained in a state in which it acts on the corresponding first cross-sectional expansion portion 21 of the foundation beam 5 or the footing 4. This causes each component to be pressed against each other. Alternatively, the fixing devices 25 may be composed of a support plate and a nut supported by the support plate and having a female thread that screws into a male thread formed on the first tension member 24.

In this way, the foundation beam 5 is made of precast concrete with the first cross-sectional enlargement 21 with the first sheath 22 formed on both ends. The first cross-sectional enlargement 21 on both ends of the foundation beam 5 is then compressed to the corresponding footing 4 by the first tension member 24 inserted into the first sheath 22. This makes it possible to shorten the time required to construct the pile foundation 2. In addition, since the foundation beam 5 is compressed to a pair of footings 4 by the first tension member 24 made of unbonded tension member, when the building 1 is removed, the foundation beam 5 can be reused by releasing the connection by the first tension member 24.

Figure 4 is a plan view of the superstructure 10, shown diagrammatically along line IV-IV in Figure 1. As shown in Figures 1 and 4, the PCa beams 15 constituting the X-direction beams 12X have second cross-sectional enlarged portions 26 at both ends, the cross-sectional area of which is enlarged compared to the intermediate portion in the material axis direction. The PCa beams 15 have a vertically long rectangular cross-sectional shape at the intermediate portion in the material axis direction, and the second cross-sectional enlarged portion 26 is enlarged over the entire beam structure compared to the intermediate portion. On the other hand, the beam portion of the PCa joint member 14 constituting the Y-direction beams 12Y has the second cross-sectional enlarged portion 26 at the tip (in the illustrated example, the cross section is also enlarged at the base end). The beam portion of the PCa joint member 14 has an I-shaped cross-sectional shape at the intermediate portion in the material axis direction, and the first cross-sectional enlarged portion 21 is enlarged at the intermediate portion of the beam structure compared to the intermediate portion. In the second cross-sectional enlargement portion 26 provided at both ends of the X-direction foundation beam 5X and the second cross-sectional enlargement portion 26 provided at the tip of the beam portion of the Y-direction foundation beam 5Y, multiple third sheaths 27 extending in the member axial direction are embedded so as to open into the enlarged portion.

A fourth sheath 28 extending in the X direction is embedded in the column portion of the PCa joint member 14 (i.e., the joint portion 11a of the column 11) in continuation with the third sheath 27 of the X direction beam 12X. The second cross-sectional enlarged portion 26 at both ends of the X direction beam 12X is crimped to the joint portion 11a of the corresponding column 11 by the second tension member 29 inserted through the third sheath 27 and the fourth sheath 28. The second tension member 29 is also an unbonded tension member, and is provided with fixing devices 25 at both ends to apply tension to the second cross-sectional enlarged portion 26 of the corresponding X direction beam 12X or the column 11. This causes each member to be crimped to each other. The beam portions of the two PCa joint members 14 constituting the Y direction beam 12Y are crimped to each other by the second tension member 29 inserted through the continuous third sheath 27 with their tips butted against each other.

In this way, the superstructure 10 can be constructed using the PCa columns 13 and PCa beams 15, which makes it possible to shorten the time required to construct not only the pile foundation 2 but also the superstructure 10. In addition, since the PCa beam 15 is pressure-attached to a pair of PCa joint members 14 by the second tendon 29 made of unbonded tendons, when the building 1 is removed, the PCa beam 15 can be reused by releasing the connection by the second tendon 29.

Figure 5 is a plan view of the pile foundation 2 corresponding to Figure 2 of the building 1 according to the first modified example. In this example, the Y-direction foundation beam 5Y, like the X-direction foundation beam 5X, has a vertically elongated rectangular cross-sectional shape in the middle in the material axis direction, which is different from Figure 2. The rest of the configuration is the same as the embodiment shown in Figure 2, so the description will be omitted. The pile foundation 2 may be configured in this way.

Figure 6 is a schematic elevation of the building 1 as viewed from the direction of the arrow VI in Figure 1. As shown in Figures 1 and 6, a footing 4 is joined to the head of the pile 3. Specifically, a pile main reinforcement 31 is embedded inside the pile 3 at a position that matches the cross-sectional shape of the column 11. The pile main reinforcement 31 protrudes upward from the head of the pile 3, and the amount of protrusion is greater than the thickness of the footing 4. The footing 4 is placed on the pile 3 so that the pile main reinforcement 31 penetrates it vertically, and the footing 4 is compressed to the pile 3 by attaching a fixing device 25 to the top of the pile main reinforcement 31 with tension applied to the pile main reinforcement 31. A long member with high tensile strength, such as PC steel wire, is used for the pile main reinforcement 31.

The pile 3 is constructed so that its upper portion protrudes significantly upward from the ground surface GL. The footing 4 is formed integrally with the head of the pile 3 and is positioned higher than the ground surface GL, and the upper portion of the pile 3 protruding upward from the ground surface GL is exposed below the footing 4. The foundation beam 5 that is pressed against the footing 4 is also positioned higher than the ground surface GL, and a space S having a predetermined height is formed between the ground surface GL and the underside of the foundation beam 5. Note that the ground surface GL refers to the surface of the ground before the pile foundation 2 is constructed, and does not refer to the surface of the ground excavated for the construction of the pile foundation 2. In addition, the ground surface GL is not limited to the surface of the ground, and may be the surface of a pavement made of concrete, asphalt, or the like applied on the ground.

The height of the space S is dimensioned so that equipment and machinery 41 of the building 1, such as an emergency generator and a distribution board, can be installed and people can install and remove, inspect and operate this equipment and machinery 41. In other words, the foundation beams 5 function as beams to support the slab of the second-lowest floor, and the space S below the foundation beams 5 can be used as the lowest floor of the building 1. In other words, the upper part of the pile foundation 2 functions as a structure that forms the lowest floor of the building 1. Therefore, it is possible to reduce the time required to construct the superstructure 10 by one floor.

The column 11 on the second floor from the bottom of the building 1 is composed of the PCa column 13 and the joint portion 11a of the PCa joint member 14, which are constructed on the footing 4. The PCa column 13 and the PCa joint member 14 are arranged on the footing 4 in this order and are pressed to the footing 4 by the third tendon 32. The third tendon 32 is also an unbonded tendon. Specifically, a fifth sheath 33 (see FIG. 14) extending vertically is embedded in the joint portion 11a of the PCa column 13 and the PCa joint member 14. The third tendon 32 is connected to the upper end of the pile main reinforcement 31 protruding from the footing 4 via a coupler (not shown). The third tendon 32 has a length that penetrates the PCa column 13 and the PCa joint member 14 and protrudes from the upper surface of the PCa joint member 14 when connected to the pile main reinforcement 31. The PCa column 13 and the PCa joint member 14 are arranged so that the third tendon 32 passes through the fifth sheath 33 (Figure 14). Tension is applied to the third tendon 32, and in this state, a fixing device 25 is attached to the top of the third tendon 32, so that the tension of the third tendon 32 is maintained in a state acting on the PCa joint member 14. As a result, the PCa joint member 14 is crimped to the PCa column 13, and the PCa column 13 is crimped to the footing 4. The three or more floors from the bottom of the building 1 are constructed in the same way.

The slab of the second-lowest floor of the building 1 is provided on top of the foundation beams 5. The slab of the third-lowest floor of the building 1 is provided on top of the beams 12. An interior unit 42 is placed and fixed on top of the slabs of the second-lowest floor or higher of the building 1. The interior unit 42 is a unit formed by assembling together the interior walls, floor, and ceiling that define a room. The interior unit 42 may include a toilet, a unit bath, a kitchen, and the like. The interior unit 42 is used as a dwelling unit when used as an apartment building, as a guest room when the building 1 is used as a hotel, and as a hospital room when the building 1 is used as a hospital ward 82, for example.

Figures 7 to 10 are explanatory diagrams of the construction procedure of the building 1 shown in Figure 1. When constructing the building 1, the work is performed in the following procedure. First, as shown in Figure 7 (A), the pile 3 is constructed at a position that matches the column 11 in the ground. The pile 3 is constructed so that the head is at a height that matches the slab of the second floor from the bottom of the building 1 as described above. Then, as shown in Figure 7 (B), the equipment machine 41 is installed in the space S of the lowest floor of the building 1, and the footing 4 is placed on the head of the pile 3. As shown in Figure 8 (C), the foundation beam 5 is placed so as to connect a pair of adjacent footings 4, and both ends of the foundation beam 5 are compressed to the corresponding footing 4 by the first tension member 24. As shown in Figure 8 (D), tension is applied to the pile main reinforcement 31, and the fixing device 25 is attached to the upper part of the pile main reinforcement 31, thereby compressing the footing 4 to the pile 3. In addition, a slab (not shown) is constructed on the upper part of the foundation beam 5. This completes the pile foundation 2 of the building 1.

Next, as shown in Fig. 9 (E), the PCa column 13 is placed on the footing 4, and the interior unit 42 is placed and fixed on the slab (not shown) of the pile foundation 2. As shown in Fig. 9 (F), the PCa joint member 14 is placed on the PCa column 13, and a pair of PCa joint members 14 that are continuous in the Y direction are pressed together with the second tendon 29. A PCa beam 15 is placed between the PCa joint members 14 adjacent to each other in the X direction, and both ends of the PCa beam 15 are pressed to the joint portion 11a of the PCa joint member 14 (see Fig. 1) with the second tendon 29. In addition, a third tendon 32 is connected to the upper end of the pile main reinforcement 31 so as to vertically penetrate the PCa column 13 and the PCa joint member 14. As shown in FIG. 10(G), tension is applied to the third tendon 32 and a fastener 25 is attached to the top of the third tendon 32, thereby crimping the PCa joint member 14 to the PCa column 13, and the PCa column 13 to the footing 4. A slab (not shown) is also constructed on top of the beam 12. This completes one story of the superstructure 10 of the building 1. If the superstructure 10 is planned to have multiple stories, the same procedure is repeated to construct each story. In this manner, the building 1 is constructed.

Figure 11 is an elevation view of the building 1 according to the second modified example, corresponding to Figure 6. As shown in Figure 11, in this example, the amount of protrusion of the pile 3 from the ground surface GL is smaller than in the above embodiment. Specifically, the footing 4 is arranged at a height that makes the lower surface coincide with the ground surface GL. The foundation beam 5 has a beam diameter smaller than the height (thickness) of the footing 4 and is arranged to match the upper surface of the footing 4. Therefore, the lower surface of the foundation beam 5 is higher than the ground surface GL, and a slight gap is formed below the foundation beam 5. Even if the pile foundation 2 is configured in this way, since the foundation beam 5 is provided at a position above the ground surface GL, it is not necessary to excavate the ground when constructing the foundation beam 5. Therefore, it is possible to shorten the time required to construct the pile foundation 2 compared to the case where the footing 4 and the foundation beam 5 are constructed after excavating the ground.

Figure 12 is a plan view of the building 1 according to the third modified example corresponding to Figure 4, and Figure 13 is an elevation view of the building 1 according to the third modified example corresponding to Figure 6. As shown in Figure 12, in this example, the Y-direction beam 12Y is composed of a PCa beam 15 made of precast concrete, just like the X-direction beam 12X. The PCa beam 15 constituting the X-direction beam 12X and the PCa beam 15 constituting the Y-direction beam 12Y are both press-fitted to the columns 11 consisting of the PCa columns 13 at the second cross-sectional enlarged portions 26 at both ends by the second tension members 29. As shown in Figure 13, the columns 11 for one floor have the length of one floor and are composed of the PCa columns 13 integrally equipped with the joint portion 11a. Even if the superstructure 10 is constructed in this way, it is possible to shorten the construction time and reuse the PCa beams 15 after the building 1 is removed, as in the above embodiment.

In the above embodiment, as explained mainly with reference to FIG. 6, the footing 4 made of precast concrete is placed on the pile 3 so that the pile reinforcement 31 provided on the pile 3 penetrates it vertically. However, if the horizontal construction error of the pile 3 is large, placing the footing 4 so that the pile reinforcement 31 penetrates the through holes provided in the footing 4 will result in the position of the footing 4 being shifted from the planned position. Therefore, as shown in FIG. 14, it is advisable to join the pile 3 and the footing 4 in a manner different from that shown in FIG. 6.

Figure 14 is a vertical cross-sectional view showing a schematic view of the main part of the building 1 shown in Figure 3 with a part broken away. As shown in Figure 14, a first recess 51 with a cross section larger than that of the pile 3 and open downward is formed on the underside of the footing 4 made of precast concrete. A sheacotter 52 consisting of a smaller recess is formed on the side and bottom surface (ceiling surface) of the first recess 51. Reinforcement bars 53 are arranged on the outer periphery of the footing 4 so as to surround the first recess 51, and the above-mentioned second sheath 23 is buried inside the footing 4. A pile main reinforcement bar 54 is buried inside the pile 3, and the pile main reinforcement bar 54 protrudes upward from the upper surface of the pile 3. The footing 4 is arranged to receive the head of the pile 3 in the first recess 51, and the first recess 51 is filled with a filler material 55 while receiving the head of the pile 3. As a result, the footing 4 is joined to the head of the pile 3 and is integrated with the pile 3. An engagement structure that engages with the filler material 55 may be provided on the outer peripheral surface of the head of the pile 3.

In this way, a first recess 51 larger than the cross section of the pile 3 is formed on the underside of the PCa member that forms the footing 4. Therefore, even if the planar position of the pile head deviates from the planned position of the column 11, the footing 4 can be positioned to match the planned position of the column 11 and joined to the pile 3 via the filler material 55. In addition, because the footing 4 is made of precast concrete, it is possible to reduce the time required to construct the pile foundation 2 compared to constructing the footing 4 with cast-in-place concrete.

An anchor 56 is embedded in the footing 4 so as to protrude upward from the upper surface. The anchor 56 is long enough that its lower end is positioned above the first recess 51, and an anchor member 57 for fixing is attached to its lower end. The PCa column 13 has a fifth sheath 33 extending vertically as described above. The upper end of the anchor 56 embedded in the footing 4 is connected to the third tendon 32 via a joint member 58. The PCa column 13 is arranged so that the third tendon 32 is inserted into the fifth sheath 33, and is crimped to the footing 4 by the third tendon 32 as described above.

In this way, the PCa column 13 is pressure-attached to the footing 4 by the third tendon 32, which is an unbonded tendon. Therefore, when the building 1 is removed, the PCa column 13 can be reused by releasing the connection by the third tendon 32.

Figure 15 is a longitudinal sectional view of the main part of the building 1 according to the fourth modified example, corresponding to Figure 14. The footing 4 of this example differs from the example of Figure 14 in that it is constructed by cast-in-place concrete. As shown in Figure 15, the footing 4 is constructed by cast-in-place concrete poured in a state in which the second sheath 23 is arranged in the formwork so as to be continuous with the first sheath 22 provided on the first cross-sectional enlargement portion 21 of the foundation beam 5. Therefore, even if the position of the pile head on the plane is shifted from the planned position of the column 11, the footing 4 can be easily constructed at a position that matches the planned position of the column 11. In addition, since the second sheath 23 is buried inside the footing 4, the first tendon 24 can be arranged to penetrate the footing 4, and the foundation beam 5 can be pressed against the footing 4 by the first tendon 24.

The upper surface of the pile 3 is formed with a second recess 61 that is open upward. The second recess 61 has a cross section that is equal to or larger than the cross section of the column 11. An anchor 56 is embedded in the footing 4 so as to protrude upward from the upper surface. The anchor 56 has a length such that its lower end enters the second recess 61, and an anchor member 57 for fixing is attached to its lower end. The PCa column 13 has a fifth sheath 33 that extends vertically as described above. The upper end of the anchor 56 embedded in the footing 4 is connected to the third tendon 32 via a joint member 58. The PCa column 13 is arranged so that the third tendon 32 is inserted into the fifth sheath 33, and is pressed against the footing 4 by the third tendon 32 as described above.

Because the second recess 61 is formed on the top surface of the pile 3 in this way, even if the planar position of the pile head deviates from the planned position of the column 11, an anchor 56 of a length that allows its lower end to be received in the second recess 61 can be provided in a position that matches the planned position of the column 11. In addition, because the PCa column 13 is pressed against the footing 4 by the third tendon 32, when the building 1 is removed, the PCa column 13 can be reused by releasing the connection by the third tendon 32.

Figure 16 is a plan view of a building 1 to explain the procedure for tensioning an unbonded tendon. Here, the steps of the tensioning work for the first tendon 24 are explained in order using a pile foundation 2 as an example, but this can also be applied to the second tendon 29 used in the superstructure 10, as described below.

As shown in FIG. 16, in preparation for tensioning the first tension members 24, three or more footings 4 are arranged in a row, and two or more foundation beams 5 are arranged in a straight line between the corresponding pairs of footings 4. Then, a plurality of first tension members 24 are arranged in a straight line so as to penetrate the footings 4 and the first cross-sectional expansion portion 21 of the foundation beams 5 to be joined thereto. Two or more first tension members 24 arranged in a straight line are connected via couplers by connecting tension members 71 to form a continuous long continuous tension member 72. Next, a jack 73 is attached to one end of the continuous tension member 72, and tension is applied to the continuous tension member 72. In this state, both ends of the plurality of first tension members 24 are fixed to the corresponding first cross-sectional expansion portion 21 or footing 4 using fixing devices 25. After the first tension members 24 are fixed, the tension of the jack 73 is released, and the connecting tension member 71 is removed.

By performing tensioning work in this manner, it is not necessary to apply tension to the first tension member 24 for each footing 4 in order to press the adjacent ends of a pair of foundation beams 5 arranged in a straight line on both sides of the footing 4 to the footing 4. This makes it possible to reduce the time required for the pressing work between the footing 4 and the foundation beams 5.

Although not shown, when tensioning the superstructure 10, the following steps are performed in order. First, three or more PCa columns 13 are arranged in a row, and two or more PCa beams 15 are arranged linearly between a pair of PCa columns 13 corresponding to each other. Then, multiple second tension members 29 are arranged in a straight line so as to penetrate the second cross-sectional expansion portion 26 of the PCa column 13 and the PCa beam 15 to be joined thereto. Two or more second tension members 29 arranged in a straight line are connected via a coupler by a connecting tension member 71 to form a continuous long continuous tension member 72. Next, a jack 73 is attached to one end of the continuous tension member 72, and tension is applied to the continuous tension member 72. In this state, both ends of the multiple second tension members 29 are fixed to the corresponding second cross-sectional expansion portion 26 or column 11 using the fixing device 25. After the second tension members 29 are fixed, the tension of the jack 73 is released, and the connecting tension member 71 is removed.

By performing tensioning work in this manner, it is not necessary to apply tension to the second tension member 29 for each PCa column 13 in order to press the adjacent ends of a pair of PCa beams 15 arranged in a straight line on both sides of the PCa column 13 to the PCa column 13. Therefore, the time required for the pressing work of the PCa column 13 and the PCa beam 15 can be shortened.

Figure 17 is an explanatory diagram of the change of use of a building 1 configured in this way. Figure 17(A) shows a front view of the building 1 used as a parking lot 81, Figure 17(B) shows a side view of the building 1 showing the use change procedure, and Figure 17(C) shows a front view of the building 1 used as a hospital ward 82.

As shown in FIG. 17(A), in this state, no interior unit 42 is provided inside the superstructure 10, and the building 1 is used as a parking lot 81. The superstructure 10 of the building 1 has multiple floors, constituting a so-called multi-storey parking lot. Vehicles can move between floors by driving themselves up a ramp provided in the building 1, or by using lifting equipment provided in the building 1 that can transport vehicles.

When an infectious disease outbreak occurs, many hospital rooms may be required to isolate infected patients. In such a case, it is conceivable that a demand will arise to use the building 1 used as a parking lot 81 as a hospital ward 82. Therefore, in this embodiment, the building 1 is remodeled by installing equipment machinery 41 and interior units 42 that can be used as hospital rooms inside the building 1, and the building 1 is used as a hospital ward 82 as shown in FIG. 17(C). The building 1 used as the parking lot 81 may be constructed within the hospital grounds, may be attached to another facility, or may be constructed as a dedicated parking lot.

When renovating the building 1, as shown in FIG. 17(B), it is advisable to install the equipment machine 41 on the lowest floor of the building 1 and the interior unit 42 on the second floor or higher from the bottom. Since the equipment machine 41 is installed on the lowest floor, the equipment machine 41 can be brought in on the ground, making the renovation work easy. Since the interior unit 42 is installed on the second floor or higher, it is advisable to hoist the interior unit 42 with a crane (not shown) and insert it horizontally from the outside of the superstructure 10, which was used as the parking lot 81, into the superstructure 10, and fix it inside the superstructure 10. In this way, the building 1, which was used as the parking lot 81, can be renovated into a hospital ward 82.

When the epidemic of the infectious disease has subsided and there is no longer a need to use the building 1 as the hospital ward 82, the building 1 that was used as the hospital ward 82 can be remodeled into a parking lot 81. Specifically, the interior unit 42 installed in the superstructure 10 can be released from its fixed position, pulled out horizontally outward from the superstructure 10, and the equipment and machinery 41 removed, thereby remodeling the building 1 and returning the superstructure 10 to the parking lot 81.

In this way, the building 1 can select between a first usage method in which the upper structure 10 is used as a parking lot 81 without installing the interior unit 42 that can be used as a hospital room, and a second usage method in which the interior unit 42 is installed inside the upper structure 10 and the upper structure 10 is used as a hospital ward 82. The parking lot 81 can be changed to a hospital ward 82 by installing the interior unit 42 inside the upper structure 10, and the hospital ward 82 can be changed to a parking lot 81 by removing the interior unit 42 from inside the upper structure 10, so that the use of the upper structure 10 can be easily changed. In addition, since the upper structure 10 can be used as a parking lot 81 or a hospital ward 82 as needed, land and construction costs are reduced compared to the case of building both. Furthermore, since the upper structure 10 can be used as a hospital ward 82 by changing the use, the hospital ward 82 can be used in a shorter time than when a new hospital ward 82 is built when needed.

Figure 18 is a plan view of building 1 showing a first use example of ward 82. As shown in Figure 18, in this example, the interior units 42 are roughly the same size as the parking spaces, and an interior unit 42 is installed in each parking space. Patients suspected of having an infectious disease or infected with an infectious disease are loaded into a vehicle and transported, isolated from contact with the outside, to the interior unit 42 that will be used as the hospital room to which they should enter. Since it is possible to install the same number of interior units 42 as there are parking spaces, it is possible to secure a large number of hospital rooms in building 1.

Figure 19 is a plan view of the building 1 showing a second use example of the ward 82. As shown in Figure 19, in this example, the interior units 42 are installed in every other parking space. In this arrangement, one of the parking spaces adjacent to the interior unit 42 can be used as a parking space for patients entering the ward. Therefore, patients who are suspected of having an infectious disease or have an infectious disease can move to their designated hospital room (interior unit 42) by themselves in their own vehicle. In addition, when they are discharged from the hospital, they can return home in their own vehicle parked next to the hospital room. Alternatively, if patient isolation is not required, the parking space next to the interior unit 42 may be used as a parking space for visitors who come to visit hospitalized patients.

Figure 20 is an elevation view of building 1 showing a third use example of a ward 82. As shown in Figure 20, in this example, the bottom floor of building 1 is used as a drive-through testing facility. Interior units 42 that can be used as hospital rooms are installed on the upper floors of building 1, and building 1 is used as a ward 82 for testing and hospitalization. The equipment and machinery 41 necessary for the ward 82 may be installed on the second floor from the bottom of building 1. In this building 1, patients suspected of having an infectious disease are tested while remaining in their vehicles on the bottom floor of building 1, and if it is determined that they have an infectious disease, the patient can enter the hospital room (interior unit 42) without coming into direct contact with outside people.

In another embodiment, building 1 may be constructed within an airport and used as a parking lot 81 during normal times, and in the event of an infectious disease outbreak, as a quarantine facility for isolating passengers entering the country from a country or region where the infection is widespread.

As explained with reference to FIG. 17, when an existing building 1 used as a parking lot 81 or the like is remodeled into a hospital ward 82 or the like, the building 1 can be remodeled in a short period of time. However, if there is no building 1 that can be repurposed in this way, a new building 1 must be constructed, which requires a certain amount of time. As described above, both ends of the foundation beam 5 are compressed to the footing 4 by the first tendon 24, so the construction time of the pile foundation 2 can be shortened. However, a relatively long period of time is required to construct the piles 3.

Therefore, if it is predicted that the building 1 will be needed suddenly, it is a good idea to construct the piles 3 in advance. For example, in preparation for future epidemics of infectious diseases or for securing evacuation shelters in the event of a disaster, it is possible to construct the piles 3 of the building 1 to be used as a hospital ward 82 or evacuation shelter in public land such as a park. By constructing the piles 3 in advance in this way, when the hospital ward 82 or evacuation shelter is suddenly needed, the pile foundation 2 can be rapidly constructed by constructing the footing 4 and using the first tension member 24 to press the foundation beam 5 to the footing 4. The superstructure 10 can also be rapidly constructed using PCa members and unbonded PC wires.

The piles 3, which are constructed in advance, should be configured so that the underside of the footing 4 is flush with the ground surface GL, as shown in Figure 11. In this way, the amount by which the piles 3 protrude from the ground surface GL is small, and the piles 3 are unlikely to get in the way under normal circumstances. Alternatively, the piles 3 can be constructed so that they do not protrude from the ground surface GL, and when constructing the footing 4, the surface layer of the ground can be excavated, or embankment can be built so that the piles 3, which protrude slightly from the ground surface GL, are hidden. In this way, the piles 3 do not get in the way under normal circumstances.

On the other hand, as shown in FIG. 6, the stakes 3 may be constructed so that they protrude significantly above the ground surface GL. In this case, the stakes 3 are visible under normal circumstances, but can also be used as monuments in parks, etc.

21A and 21B are perspective and longitudinal sectional views showing an example of the use of pre-constructed piles 3. As shown in FIG. 21A, in this example, the piles 3 are constructed at a height that does not protrude from the ground surface GL. The piles 3 are arranged at a predetermined interval in the X and Y directions (see FIG. 1). A balancing pond 90 is provided in an area surrounded by a plurality of piles 3, and the piles 3 are used as part of the structure of the balancing pond 90. Retaining walls 91 are provided between the piles 3 adjacent to each other in the X and Y directions, and a resin storage structure 92 is provided in a position surrounded by the piles 3 and the retaining wall 91. As shown in FIG. 21B, a waterproof sheet 93 is laid around the storage structure 92, and soil 94 is backfilled between the waterproof sheet 93 and the retaining wall 91. With this configuration, the upper part of the balancing pond 90 can be opened and used as part of a park, etc.

In this way, when building 1 is constructed when needed and used for a certain purpose, it is possible that building 1 will no longer be needed. In this case, building 1 can be renovated and used for a different purpose as described above, but it is also possible to dismantle building 1 and move it to another location for reuse.

In other words, if the superstructure 10 is constructed by crimping PCa members with unbonded tendons, the unbonded tendons can be released from the crimp, the PCa members can be dismantled, transported to another location, and then reassembled to construct the superstructure 10.

For the pile foundation 2, the compression by the first tension member 24 can be released to dismantle the foundation beam 5, and the foundation beam 5 can be reused for a building 1 to be constructed in a different location. The piles 3 and footing 4 cannot be dismantled and reused in the configurations shown in Figures 14 and 15. On the other hand, when the footing 4 is compressed to the piles 3 by the pile main reinforcement 31 as shown in Figure 6, the compression by the pile main reinforcement 31 can be released to dismantle the footing 4, and the footing 4 can be reused for a building 1 to be constructed in a different location.

Although the description of the specific embodiment is now complete, the present invention is not limited to the above embodiment and can be modified in a wide range of ways. For example, the specific configuration and arrangement of each member or part, the quantity, materials, construction procedures, etc. can be changed as appropriate without departing from the spirit of the present invention. On the other hand, not all of the components shown in the above embodiment are necessarily required and can be selected as appropriate.

1: Building 2: Pile foundation 3: Pile 4: Footing 5: Foundation beam 5X: X-direction foundation beam 5Y: Y-direction foundation beam 10: Superstructure 11: Column 11a: Joint portion 12: Beam 12X: X-direction beam 12Y: Y-direction beam 13: PCa column 14: PCa joint member 15: PCa beam 21: First cross-sectional enlargement portion 22: First sheath 23: Second sheath 24: First tension member 25: Fixing device 26: Second cross-sectional enlargement portion 27: Third sheath 28: Fourth sheath 29: Second tension member 32: Third tension member 33: Fifth sheath 41: Equipment machine 42: Interior unit 51: First recess 55: Filler material 56: Anchor 61: Second recess 71: Connecting tension member 72: Continuous tension member 81: Parking lot 82 : Ward

Claims (4)

A method for constructing a building having a superstructure including a plurality of PCa columns made of precast concrete and PCa beams made of precast concrete connecting a pair of adjacent PCa columns, comprising:
A step of preparing a plurality of PCa beams each having a second cross-sectional enlarged portion at both ends, the second cross-sectional enlarged portion having a third sheath extending in a member axial direction;
Preparing a plurality of PCa columns each having a fourth sheath that is to be continuous with the third sheath;
Arranging three or more of the PCa columns in a row;
A step of linearly disposing two or more of the PCa beams between a pair of the PCa columns corresponding to each of the PCa beams;
A step of arranging a plurality of tendons in a collinear line so as to penetrate the second cross-sectional enlarged portion of the PCa column and the PCa beam to be joined thereto;
a step of connecting two or more of the tendons arranged on the same straight line with a connecting tendon to form a single continuous long tendon;
A method for constructing a building, comprising the steps of applying tension to the continuous tension member and fixing both ends of the plurality of tension members to the corresponding second cross-sectional expansion portion or PCa column. The method for constructing a building according to claim 1, characterized in that the tendons are unbonded tendons that are not attached to the PCa columns and the PCa beams . A method for constructing a building with a pile foundation including a plurality of footings integrally provided on the heads of a plurality of piles and a foundation beam connecting a pair of adjacent footings, comprising:
A step of preparing a plurality of the foundation beams made of precast concrete, each of which has a first cross-sectional enlarged portion formed at both ends and which includes a first sheath extending in a material axial direction;
placing three or more of said footings in a row;
positioning two or more of the foundation beams in a straight line between a corresponding pair of the footings;
A step of arranging a plurality of tendons in a collinear line so as to penetrate the footing and the first cross-sectional enlarged portion of the foundation beam to be joined thereto;
a step of connecting two or more of the tendons arranged on the same straight line with a connecting tendon to form a single continuous long tendon;
and applying tension to the continuous tendon and fixing both ends of the plurality of tendons to the corresponding first cross-sectional enlarged portion or the footing. 4. The method for constructing a building according to claim 3, wherein the tendons are unbonded tendons that are not attached to the footing and the foundation beam.

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